Interfacial instability of amorphous LiPON against lithium: A combined Density Functional Theory and spectroscopic study
Interfacial instability of amorphous LiPON against lithium: A combined Density Functional Theory and spectroscopic study
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DOI：
10.1016/j.jpowsour.2017.04.005
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发表时间：
2017-06
影响因子：
9.2
通讯作者：
S. Sicolo;M. Fingerle;R. Hausbrand;K. Albe
中科院分区：
文献类型：
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作者：
S. Sicolo;M. Fingerle;R. Hausbrand;K. Albe
结合表面科学方法和量子力学计算研究了玻璃态固体电解质LiPON对金属锂的化学不稳定性及其界面副反应的发生。使用进化结构搜索，然后通过熔融淬火协议，生成LiPON无序结构的模型，并与锂接触。即使是一个简单的模型界面的静态优化表明，锂扩散到LiPON是由一个相当大的驱动力，可以很容易地发生在实验条件下。计算的反应能表明，LiPON的还原和分解是热力学上有利的。通过监测作为锂暴露的函数的LiPON核心水平的演变，观察到LiPON网络的中断以及新阶段的发生。UV光电子能谱测量和计算的电子态密度之间的直接比较，为增加阶段的锂化明确地确定新的相为Li2O，Li3P和Li3N。这些产物对Li金属是稳定的，并形成钝化层，其保护电解质免于进一步分解，同时允许Li离子扩散。
The chemical instability of the glassy solid electrolyte LiPON against metallic lithium and the occurrence of side reactions at their interface is investigated by combining a surface science approach and quantum-mechanical calculations. Using an evolutionary structure search followed by a melt-quenching protocol, a model for the disordered structure of LiPON is generated and put into contact with lithium. Even the static optimization of a simple model interface suggests that the diffusion of lithium into LiPON is driven by a considerable driving force that could easily take place under experimental conditions. Calculated reaction energies indicate that the reduction and decomposition of LiPON is thermodynamically favorable. By monitoring the evolution of the LiPON core levels as a function of lithium exposure, the disruption of the LiPON network alongside the occurrence of new phases is observed. The direct comparison between UV photoelectron spectroscopy measurements and calculated electronic densities of states for increasing stages of lithiation univocally identifies the new phases as Li2O, Li3P and Li3N. These products are stable against Li metal and form a passivation layer which shields the electrolyte from further decomposition while allowing for the diffusion of Li ions.